This invention relates to two component compositions of the type comprising a first component which is a crosslinkable film forming or matrix forming component and a second component which is an isocyanate crosslinking agent for said first component. More particularly, the invention relates to thermosetting compositions of the aforementioned type wherein the first component is an oligomeric hydroxy functional phosphate ester and the second component is a polyisocyanate. Compositions within this scope of the invention are particularly useful as coating compositions, most particularly high solids coating compositions, and as molding compositions, most particularly compositions for reaction injection molding.
Acrylic polymers and polyesters comprise the major resin components in many automotive topcoats and primers as well as many molding compositions. Replacement of a --CH(CH.sub.3)-- by --P(CH.sub.3)-- or --(CH.sub.3) P(O)-- in such acrylics and polyesters does not change the general physical properties. However, it is known that flammability is significantly reduced. In addition to increased polarity and nonflammability, special effects can be assigned to various organophosphate groups. For example, it has been found that incorporation of organophosphorous esters (P-O-alkyl, P-O-aryl), both in the main chain of the polymer and in pendent groups leads to pronounced internal plasticization, which is accompanied by a lower softening temperature, and an increase in impact strength and a higher elongation at rupture. In addition to some of the above desirable properties, organophosphorous esters have also been reported to be radiation stabilizers and antioxidants.
It has now been discovered that a novel class of hydroxy functional organophosphorous oligomeric esters are particularly suitable for preparation of compositions which are crosslinked by aliphatic, cycloaliphatic or aromatic polyisocyanates. Compositions thus prepared afford high solids, low bake coatings with excellent hardness, adhesion, gloss, solvent resistance, impact strength and elongation, while also being particularly suitable for use in molding applications including reaction injection molding.